1). Field of the Invention
This invention relates in general to process for the conversion of normorphinone and its derivatives, which can be synthesized from morphine, to the corresponding 14-hydroxynormorphinone and its derivatives including oxycodone, oxymorphone, noroxymorphone, and naltrexone. Noroxymorphone is a key intermediate for the production of important narcotic analgesics and antagonists. In another aspect, the invention is directed to certain novel intermediates.
2). Background Art
14-Hydroxy-substituted morphine derivatives are important narcotic analgesics and/or antagonists. These drugs include oxycodone, oxymorphone, nalbuphine, naloxone, naltrexone, and nalmefene. They are readily synthesized from thebaine, which is a minor component of gum opium. As the supply of thebaine is limited and the demand is increasing, therefore, the price of thebaine is high. As a result, many alternative approaches have been made for the preparation of 14-hydroxymorphine derivatives.
The reported efforts for preparing these narcotics bearing a 14-hydroxy group from readily abundant starting materials morphine or codeine (a minor component of gum opium, which may also be synthesized by methylation of morphine) are summarized as the following: (1) the conversion of codeine to thebaine through dihydrocodeinone (5.4% yield, H. Rapoport, et al., J. Am. Chem. Soc., vol. 89, 1967, p. 1942 and H. Rapoport, et al., J. Org. Chem., vol. 15, 1950, p. 1103), codeinone (20% yield, I. Seki, Chem. Pharm. Bull., vol. 18, 1970, p. 671 and H. Rapoport, et al., J. Am. Chem. Soc., vol. 77, 1955, p. 490) or 6-methyl ether of codeine (using manganese dioxide, 67% yield, R. B. Barber, et al., J. Med. Chem., vol. 18, 1975, p. 1074); (2) the oxidation of codeinone pyrrolidinyl di-enamine to 14-hydroxycodeinone (30-40% yield, I. Seki, Chem. Pharm. Bull., vol. 18, 1970, p. 671); (3) the direct allylic oxidation of codeine to the corresponding 14-hydroxy derivatives with manganese dioxide (I. Brown, et al., J. Chem. Soc., 1960, p. 4139), and selenium dioxide plus t-butyl hydrogen peroxide (M. A. Schwartz, et al., J. Med. Chem., vol. 24, 1981, p. 1525); and (4) the six-step transformation of codeine to noroxycodone (52% yield) and noroxymorphone (43% yield) using photochemically generated singlet oxygen (M. A. Schwartz, et al., J. Med. Chem. vol. 24, 1981, p. 1525); and (5) the preparation of noroxymorphone from morphine through an intermediate with carbamate protection on the nitrogen atom (17-position) or a carbonate protecton at the 3 position and the carbamate protection at the 17 position of normorphinone dienol acetate with MCPBA in the substantial absence of water (37% yield, Wallace, U.S. Pat. No. 5,112,975). These processes suffer from either low yields, long steps, not amenable to scale-up, or involve the use of environmentally unfriendly heavy metals.
It is therefore an object of the present invention to provide methods for the conversion of normorphinone and its derivatives to the corresponding 14-hydroxynormorphinone and its derivatives. A further object of the invention is to provide processes which provide relatively high yields of the desired products. Another object is to provide methods which are environmentally safe and avoid the use of heavy metals.
Another object of the present invention is to provide processes which can use morphine or codeine as starting material instead of the scarce thebaine. Codeine is a component of gum opium and can also be produced by methylation of morphine using known prior art techniques. A still further object of the present invention is to provide the use of an aqueous system in the oxidation step to form 14-hydroxynormorphinone
wherein Q and Q' are individually selected from hydrogen, lower alkyl, trifluoromethyl, nitro, dialkylamino, cyano;
preferably, R is methyl (when the desired products are oxycodone and oxymorphone), cyclopropylmethyl (when the desired products are naltrexone and nalmefene), cyclobutylmethyl (when the desired product is nalbuphine), and benzyl (when the desired products are naloxone, naltrexone, nalbuphine, or nalmefene); PA1 preferably, R' is methyl (when the desired product is oxycodone), benzyl (when the desired products are oxymorphone and 14-hydroxyl-normorphinones), or acyl (when the desired product is oxymorphone) and R" is methyl; PA1 from the corresponding normorphinones having the formula: ##STR1## wherein R and R' are as defined above; by reacting the normorphinones (as defined above) either (1) or (2) of the following processes: PA1 X is Cl or Br, preferably Cl; PA1 and the corresponding acid salt having the formula: EQU R"COOM PA1 M is sodium or potassium atom, preferably sodium atom; PA1 (a) the conversion of the 17(N),3(O)-substituted normorphinone having the formula: ##STR5## to the corresponding 14-hydroxy-17(N),3(O)-substituted-normorphinone having the formula: ##STR6## with hydrogen peroxide in an aqueous system in the presence of an acid; (b) the conversion of the 17(N),3(O)-substituted-normorphinone dienol acylate having the formula: ##STR7## to the corresponding 14-hydroxy-17(N),3(O)-substituted-normorphinone having the formula: ##STR8## with an oxidizing agent chosen from aqueous hydrogen peroxide or a peroxycarboxylic acid in an aqueous system in the presence of a weak organic acid; PA1 (c) the oxidation reaction to form 14-hydroxy-17(N),3(O)-substituted-normorphinone having the formula: ##STR9## in an acetic aqueous system, which is very desirable for the following catalytic hydrogenation step; PA1 (d) the 14-hydroxy 3(O)-substituted and/or 17(N)-substituted-normorphinone having the formula: ##STR10## may further react in specific ways to form oxycodone, oxymorphone, naltrexone, and noroxymorphone. The later is a common intermediate for naloxone, naltrexone, nalmefene, and nalbuphine; PA1 (e) the choice of a preferred substitution group depends on the kind of desired product in such a way to facility the ease of operation, solvent and reagent consumption. PA1 (a) the use of a currently abundant starting material, codeine, which is a minor component of gum opium and can also be produced by methylation of morphine using prior art techniques. This method does not need to demethylate the N-methyl group on the 17 position of codeine, protect the 17-nitrogen of norcodeine and norcodeinone with a carbamate and then deprotect the 14-hydroxy-N-ethoxycarbonylnorcodeinone, finally, remethylate the same nitrogen as disclosed in U.S. Pat. Nos. 4,472,253, 4,639,520 and 4,795,813; PA1 (b) the use of an aqueous system in the oxidation of normorphinones or normorphinone dienol acyletes is not only environmentally friendly but also desirable for the following hydrogenation reaction, since there is no need to isolate the intermediate 14-hydroxycodeinone. The basic nitrogen on the 17-position is protonated in the acidic aqueous system. This greatly contributes to the high solubility of the reactant and the product. PA1 (a) the first step is to protect the phenolic hydroxy on the 3-position of morphine to form the 3(O)-protected-morphine having the formula: ##STR15## wherein P=P.sub.1 or R.sub.2. P is a suitable protecting group which is stable under the reaction conditions and easily removable by mild hydrolysis with an acid or base (for P.sub.1) or under catalytic hydrogenation (for P.sub.2). P.sub.1 includes acyl, benzoyl and alkoxycarbonyl. P.sub.2 includes benzyl, substituted benzyl and benzyloxycarbonyl. PA1 (b) the second step is to oxidize the 3(O)-protected morphine to 3(O)-protected-morphinone having the formula: ##STR16## by any of the prior art methods such as Swern oxidation (DMSO/acid halide or acid unhydrite). PA1 (c) the third step is to convert the 3(O)-protected-morphinone to the 14-hydroxy-3-(O)-protected-morphinone using the techniques disclosed in this invention as set forth in the conversion of codeinone to 14-hydroxycodeinone in the synthesis of oxycodone. The intermediate, 3(O)-protected-codeinone dienol acylate, is a novel compound having the formula: ##STR17## wherein P and R" are as defined above; preferably P.sub.1 is acetyl and P.sub.2 is benzyl. PA1 (d) depending on the particular protection group, P.sub.1 or P.sub.2, the fourth step is either (i) to first produce the 7,8-double bond of 3-(O)-P.sub.1 -protected morphinone and then to remove the protection group by acid or base hydrolysis to produce oxymorphone or (ii) to hydrogenate the 7,8-double bond and deprotect simultaneously the 3-(O)-P.sub.2 -protected morphinone to oxymorphone.
R' is methyl, ethyl, 2-(4-morpholinyl)ethyl, benzyl, substituted-benzyl (as defined above), benzyloxycarbonyl or the group having the formula: EQU R"C(O)-- PA2 (1) directly with an oxidizing agent, hydrogen peroxide, at a temperature of about 15.degree. C. to about 70.degree. C., preferably 40.degree. C. to 50.degree. C., in the presence of an acid such as formic which is not only environmentally friendly, but also desirable in which to conduct the subsequent hydrogenation reaction without the need for isolating the 14-hydroxynormorphinone intermediate. A still further object is to provide certain intermediates which are novel compositions. It is a further object of this invention to provide intermediates for specific products, such as oxycodone, oxymorphone, naltrexone and noroxymorphone. These and other objects will readily become apparent to those skilled in the art in light of the teachings herein disclosed. PA2 (2) in a two-step manner by first with an acyl halide having the formula: EQU R"C(O)X
wherein: R" is lower alkyl of 1-4 carbon atoms;